As is known, in the treatment of bone fractures and/or breaks, particularly of “long” bones, such as the femur, tibia or humerus, one or more connecting members, typically comprising metal pins, are inserted inside the medullary canal of the bone to immobilize the bone fracture and prevent any relative rotation between the fractured bone portions.
Systems of the above type substantially comprise inserting a metal pin inside the medullary canal of the bone through an incision in the skin; and subsequently anchoring the pin to the bone portions by means of screws—so-called proximal and distal screws—each of which is connected and fixed to the metal pin at a respective reference point or so-called “gauge point”.
The reference point is typically located at a transverse through hole formed in the body of the metal pin to receive the stem of a respective screw and anchor the pin to the bone portions. More specifically, the reference points of proximal screw holes are located on an end portion of the metal pin located, in use, at the skin incision, while the reference points of distal screw holes are located on the opposite end portion of the metal pin located, in use, further away from the skin incision.
When anchoring the pin, the reference points of the proximal screws are fairly easy to determine from the outside, whereas determining the reference points of the distal screw holes is extremely complicated.
Once the metal pin is inserted inside the medullary canal, the reference points are currently determined with the aid of a radioscopic system comprising an external device for emitting a diverging beam of X-rays onto the limb into which the pin has been inserted, and an X-ray detector for determining the X-ray absorption pattern in the area traversed by the beam, and displaying a radiological image of the limb and associated pin on a screen. In actual use, the surgeon determines a reference point on the basis of the radioscopic image, which also shows, instant by instant, the position of the drill bit before and as the bone portion is drilled from the outside.
The above radioscopic system has the major drawback of not allowing the surgeon to determine the reference points quickly and accurately. That is, the radioscopic image shows the surgeon the location of the reference point in a two-dimensional plane, but gives no indication of its location in the third dimension. As a result, the surgeon is forced to determine the reference point by highly invasive trial and error, during which, both the surgeon and patient are exposed to X-rays, with obvious harmful effects on the health of the patient, and particularly of the surgeon who is exposed repeatedly to such radiation.
EP-A-1.195.143 discloses a connecting member able to be inserted inside a bone structure. The connecting member comprises at least one electrical signal generator located at a predetermined reference point of the connecting member.
U.S. Pat. No. 6,080,099 discloses a seed including a capsule containing a radioisotope for radio-therapeutic use.